Flexible Covershield for Thin Film Solar Arrays (PDRT09-031-1)

ABSTRACT: Thin film solar arrays using advanced Inverted Metamorphic solar cells can offer a significant increase in efficiency and specific power over conventional planar solar arrays for future spacecraft. The flexible low-mass solar cells require an equally flexible robust replacement to the conventional coverglass technology to fully realize both low specific power and deployment flexibility. This SBIR develops a flexible Conductive CoverGlass Replacement (CCGR) technology that will protect the solar cells from harsh spacecraft environments, while maintaining transparency through End of Life and assuring sufficient conductivity to mitigate ESD effects, so as to ensure that the high efficiency promised by IMM cells can be realized. The approach uses advanced nanotechnology to enhance the electrical conductivity and environmental robustness of space-qualified silicone materials. In this program, the properties of metallic nanoparticles will be evaluated and integrated with POSS nanoparticles to form a multi-functional coating that will provide electrical conductivity and resistance to radiation and atomic oxygen. Methods for integration onto thin film solar cell modules will be developed, and flight-representative test articles will undergo radiation exposure and thermal vacuum qualification tests. The result will be thin film modules that incorporate CCGR technology that are ready for space qualification testing. BENEFIT: The anticipated benefits of the IMM solar cell module with Conductive Coverglass Replacement include much higher specific power, in terms of Watts/kilogram and stowed volume efficiency, in terms of Watts/cubic-meter. This can enable a high power array that can package into a smaller envelope and be launched on smaller, lower cost launch vehicles. The research will also increase solar array robustness at reduced cost by providing a contiguous flexible shield instead of individual cover-glasses on the cells. This technology can also apply to other thin film solar cell technologies, and as a replacement for conductively coated glass in other applications, such as Optical Solar Reflectors for thermal control surfaces. The nano-structured material may also benefit other applications where enhanced electrical conductivity or selective absorptance may be needed, including structural grounding, thermal transport, and thermal control surfaces.